In order to fit a musical module to a musical box in the form of a watch, the size of all of the components of the musical module must be reduced, while continuing to offer a varied melody, good quality sound and a high acoustic level. WO Patent No. 2008/007161 discloses such a musical module for a watch movement. The musical module includes at least one pin-barrel. The pin-barrel is formed of several metal strips or blades, arranged parallel to each other in one plane and connected to a heel, which is fixed to a watch plate. Each strip is capable of producing one sound of determined tonality according to its length. The strips are activated by pins of a rotating disc to produce a musical sound. The pins distributed over the rotating disc can raise or bend at least some of the strips and release them, causing them to vibrate, so as to produce a musical sound.
The acoustic performance, such as the duration of vibration of the activated strip or strips, depends upon several factors. These factors concern the geometry of each strip, such as the height and length thereof, the properties of the material, such as the modulus of elasticity, density and internal damping, any heat treatment or clamping or securing of the pin-barrel. If the size of the components of the musical module, which includes the pin-barrel, is reduced, the duration of vibration of the activated strips may be short, since the internal friction in the watch becomes greater relative to the effective mass of the pin-barrel. Even with the best possible pin-barrel for a musical module, which takes account of the aforementioned factors, it is difficult to optimise the duration of vibration of the activated pin-barrel strips of a musical box in the form of a watch, without obtaining undesired effects.